Light emitting device and fabricating method thereof

ABSTRACT

A light emitting device includes a plurality of unit light emitting regions on a substrate. At least one of the unit light emitting regions includes at least one pair of first and second electrodes that are spaced apart, at least one first bar-type LED in a first layer on the substrate, and at least one second bar-type LED in a second layer on the substrate. At least one of the first bar-type LED or the second bar-type LED is electrically connected between the first electrode and the second electrode.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/273,694, filed Feb. 12, 2019, which is a continuation of U.S. patentapplication Ser. No. 15/650,083, filed Jul. 14, 2017, now U.S. Pat. No.10,211,418, which claims priority to and the benefit of Korean PatentApplication No. 10-2016-0090207, filed Jul. 15, 2016, the entire contentof both of which is incorporated herein by reference.

BACKGROUND 1. Field

One or more embodiments described herein relate to a light emittingdevice and a method for fabricating a light emitting device.

2. Description of the Related Art

Light emitting diodes (LEDs) exhibit relatively satisfactory durability,even in poor environmental conditions, and have excellent performance interms of lifespan and luminance. One technique for fabricating amicro-bar-type LED on a micro or nano scale involves forming aninorganic crystal structure. This technique involves growing anitride-based semiconductor. The small size of bar-type LEDs make thensuitable for use in pixels of a self-luminescent display panel.

SUMMARY

In accordance with one or more embodiments, a light emitting deviceincludes a plurality of unit light emitting regions on a substrate,wherein at least one of the unit light emitting regions includes: atleast one pair of first and second electrodes that are spaced apart; atleast one first bar-type LED in a first layer on the substrate; and atleast one second bar-type LED in a second layer on the substrate,wherein at least one of the first bar-type LED or the second bar-typeLED is electrically connected between the first electrode and the secondelectrode.

The first bar-type LED and the second bar-type LED may emit light ofdifferent colors, and one of the first and second bar-type LEDs having alonger wavelength than the other bar-type LED may be closer to thesubstrate. At least one end of at least one of the first bar-type LED orthe second bar-type LED may be an electrically floated end.

The unit light emitting regions include a first unit light emittingregion in which the first bar-type LED is electrically connected betweenthe first electrode and the second electrode; and a second unit lightemitting region in which the second bar-type LED is electricallyconnected between the first electrode and the second electrode.

At least one of the unit light emitting regions may include at least onethird bar-type LED in a third layer on the substrate. The unit lightemitting regions include a first unit light emitting region in which thefirst bar-type LED is electrically connected between the first electrodeand the second electrode, the first unit light emitting region emittinglight of a first color; a second unit light emitting region in which thesecond bar-type LED is electrically connected between the firstelectrode and the second electrode, the second unit light emittingregion emitting light of a second color; and a third unit light emittingregion in which the third bar-type LED is electrically connected betweenthe first electrode and the second electrode, the third unit lightemitting region emitting light of a third color.

First ends of the first bar-type LED, the second bar-type LED, and thethird bar-type LED may be commonly connected to the first electrode, andsecond ends of the first bar-type LED, the second bar-type LED, and thethird bar-type LED may be commonly connected to the second electrode.

The light emitting device may include a first insulating layer betweenthe first bar-type LED and the second bar-type LED; a second insulatinglayer between the second bar-type LED and the third bar-type LED; and athird insulating layer on the third bar-type LED. At least one of thefirst bar-type LED, the second bar-type LED, or the third bar-type LEDmay be aligned such that a first end of at least one of the firstbar-type LED, the second bar-type LED, or the third bar-type LEDoverlaps the first electrode and a second end of at least one of thefirst bar-type LED, the second bar-type LED, or the third bar-type LEDoverlaps the second electrode.

At least one of the unit light emitting regions may include a firstcontact electrode penetrating the first insulating layer, the secondinsulating layer, and the third insulating layer, the first contactelectrode electrically connecting, to the first electrode, one end of atleast one of the first bar-type LED, the second bar-type LED, or thethird bar-type LED; and a second contact electrode penetrating the firstinsulating layer, the second insulating layer, and the third insulatinglayer, the second contact electrode electrically connecting, to thesecond electrode, the other end of at least one of the first bar -typeLED, the second bar-type LED, or the third bar-type LED.

The first electrode may be electrically connected to a first end of thefirst bar-type LED, and the second electrode is electrically connectedto a second end of the first bar-type LED, and at least one of the unitlight emitting regions includes a third electrode electrically connectedto a first end of the second bar-type LED and a fourth electrodeelectrically connected to a second end of the second bar-type LED.

In accordance with one or more other embodiments, a method forfabricating a light emitting device includes forming at least one pairof first and second electrodes in each of unit light emitting regions ona substrate; injecting at least one first bar-type LED into the unitlight emitting regions; forming a first insulating layer over the firstbar-type LED; injecting at least one second bar-type LED onto the firstinsulating layer; forming a second insulating layer over the secondbar-type LED; and forming a first contact electrode such that the firstelectrode is electrically connected to a first end of at least one ofthe first bar-type LED and the second bar-type LED, and forming a secondcontact electrode such that the second electrode is electricallyconnected to a second end of the bar-type LED at least connected to thefirst contact electrode.

The unit light emitting regions may include a first unit light emittingregion and a second unit light emitting region, and the method mayinclude after the first bar-type LED is injected, aligning the firstbar-type LED between the first and second electrodes of the first unitlight emitting region; and after the second bar-type LED is injected,aligning the second bar-type LED between the first and second electrodesof the second unit light emitting region. Aligning the first bar-typeLED may include applying a first voltage between the first and secondelectrodes of the first unit light emitting region, and aligning thesecond bar-type LED may include applying a second voltage greater thanthe first voltage between first and second electrodes of second unitlight emitting region.

The method may include aligning at least one of the first or secondbar-type LEDs such that ends of at least one of the first or secondbar-type LEDs are on the first and second electrodes, respectively.Forming the first and second contact electrodes may include forming afirst contact hole penetrating the first and second insulating layers toexpose a first end of at least one of the first or second bar-type LEDsand at least one region of the first electrode and a second contact holepenetrating the first and second insulating layers to expose a secondend of at least one of the first or second bar-type LEDs and at leastone region of the second electrode; forming a first contact electrode tobe buried in the first contact hole, and forming a second contactelectrode to be buried in the second contact hole.

The method may include, after the first bar-type LED is injected,aligning the first bar-type LED such that ends of the first bar-type LEDare on the first and second electrodes, respectively; and after thesecond bar-type LED is injected, aligning the second bar-type LED suchthat ends of the second bar-type LED are on the first and secondelectrodes, respectively.

Forming the first and second contact electrodes may include forming afirst contact hole penetrating the first and second insulating layers toexpose at least one region of the first electrode and first ends of thefirst and second bar-type LEDs and a second contact hole penetrating thefirst and second insulating layers to expose at least one region of thesecond electrode and second ends of the first and second bar-type LEDs;and forming, in the first contact hole, a first contact electrodecommonly connecting the first electrode to first ends of the first andsecond bar-type LEDs, and forming, in the second contact hole, a secondcontact electrode commonly connecting the second electrode to secondends of the first and second bar-type LEDs.

The method may include injecting at least one third bar-type LED ontothe second insulating layer; and forming a third insulating layer overthe third bar-type LED. The method may include, after the first bar-typeLED is injected, aligning the first bar-type LED to be electricallyconnected between the first and second electrodes, wherein forming thefirst and second contact electrodes includes: forming a conductive layeron the second bar-type LED; and patterning the conductive layer to forma third electrode connected to one end of the second bar-type LED and afourth electrode connected to the other end of the second bar-type LED.

BRIEF DESCRIPTION OF THE DRAWINGS

Features will become apparent to those of skill in the art by describingin detail exemplary embodiments with reference to the attached drawingsin which:

FIG. 1 illustrates an embodiment of a bar-type LED;

FIG. 2 illustrates an embodiment of a light emitting device;

FIGS. 3A-3E illustrate various embodiments of unit light emittingregions of a light emitting device;

FIGS. 4A-4C illustrate various embodiments of unit light emittingregions of a light emitting device;

FIG. 5 illustrates an embodiment of a unit light emitting region of alight emitting device;

FIG. 6 illustrates a view along section line I-I′ in FIG. 5;

FIG. 7 illustrates an embodiment of a unit light emitting region of alight emitting device;

FIG. 8A illustrates a sectional view one region of a light emittingdevice according to an embodiment, and FIG. 8B illustrates a plan viewof the one region of a light emitting device;

FIG. 9 illustrates a section view of one region of a light emittingdevice according to another embodiment;

FIGS. 10A-10E illustrate various stages of an embodiment of a method forfabricating the light emitting device in FIG. 8A;

FIGS. 11A-11C illustrate embodiments of one region of the light emittingdevices in FIGS. 10A-10C;

FIG. 12 illustrates a sectional view of one region of a light emittingdevice according to another embodiment;

FIGS. 13A-13E illustrate various stages in another embodiment of amethod for fabricating the light emitting device in FIG. 12;

FIG. 14 illustrates a sectional view of one region of a light emittingdevice according to another embodiment;

FIGS. 15A-15I illustrate various stages in another embodiment of amethod for fabricating the light emitting device in FIG. 14;

FIG. 16 illustrates a sectional view of one region of a light emittingdevice according to another embodiment; and

FIG. 17 illustrates a sectional view of one region of a light emittingdevice according to another embodiment.

DETAILED DESCRIPTION

Example embodiments will now be described more fully hereinafter withreference to the accompanying drawings; however, they may be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey exemplary implementations to those skilled in the art.

In the drawing figures, the dimensions of layers and regions may beexaggerated for clarity of illustration. It will also be understood thatwhen a layer or element is referred to as being “on” another layer orsubstrate, it can be directly on the other layer or substrate, orintervening layers may also be present. Further, it will be understoodthat when a layer is referred to as being “under” another layer, it canbe directly under, and one or more intervening layers may also bepresent. In addition, it will also be understood that when a layer isreferred to as being “between” two layers, it can be the only layerbetween the two layers, or one or more intervening layers may also bepresent. Like reference numerals refer to like elements throughout.

Hereinafter, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.However, the present disclosure is not limited to the embodiments butmay be implemented into different forms. These embodiments are providedonly for illustrative purposes and for full understanding of the scopeof the present disclosure by those skilled in the art. In the entirespecification, when an element is referred to as being “connected” or“coupled” to another element, it can be directly connected or coupled tothe another element or be indirectly connected or coupled to the anotherelement with one or more intervening elements interposed therebetween.

FIG. 1 illustrates an embodiment of a bar-type LED which includes anactive layer 12 between first and second conductive semiconductor layers11 and 13. The bar-type LED may have, for example, as a stack structurein which the first conductive semiconductor layer 11, the active layer12, and the second conductive semiconductor layer 13 are sequentiallystacked.

In some embodiments, the bar-type LED may further include an insulatingfilm 14 and/or first and second electrodes. The first electrode may beelectrically connected to the first conductive semiconductor layer 11.The second electrode may be electrically connected to the secondconductive semiconductor layer 13. For example, the first electrode maybe electrically connected to the bar-type LED through one surface of thefirst conductive semiconductor layer 11 (e.g., in FIG. 1, a lowersurface of the bar-type LED) which is not covered by the insulating film14. The second electrode may be electrically connected to the bar-typeLED through one surface of the second conductive semiconductor layer 13(e.g., in FIG. 1, an upper surface of the bar-type LED), which is notcovered by the insulating film 14.

In some embodiments, a conductive contact layer may be further providedbetween the first electrode and the first conductive semiconductor layer11 and/or between the second electrode and the second conductivesemiconductor layer 13. In addition, in some embodiments, the insulatingfilm 14 may allow at least one region of a side surface of the firstconductive semiconductor layer 11 and/or a side surface of the secondconductive semiconductor layer 13 to be exposed. In the embodiment, thetype and/or position of the insulating film 14 may be different inanother embodiment.

The bar-type LED in FIG. 1 has a cylindrical shape. In anotherembodiment, the bar-type LED may have various polygonal column shapesincluding a rectangular parallelepiped shape, or another shape. Forexample, the bar-type LED may have a rod or bar shape which is longer ina length direction than a width direction (e.g., an aspect ratio greaterthan 1). Thus, the length of the bar-type LED may be greater than itsdiameter or width. The size of the diameter and/or length of thebar-type LED may be, for example, in the micro or nano scale. Thesesizes may be in a different size scale in another embodiment.

The first conductive semiconductor layer 11 may include, for example, atleast one n-type semiconductor layer. For example, the first conductivesemiconductor layer 11 may include at least one of InAlGaN, GaN, AlGaN,InGaN, AlN, or InN. The first conductive semiconductor layer 11 mayinclude a semiconductor layer doped with a first conductive dopant,e.g., Si, Ge, or Sn. The material of the first conductive semiconductorlayer 11 may be different in another embodiment.

The active layer 12 is on the first conductive semiconductor layer 11and may be formed in a single or multiple quantum well structure. Insome embodiments, a clad layer doped with a conductive dopant may beformed over and/or under the active layer 12. For example, the cladlayer may be an AlGaN layer or InAlGaN layer. In embodiment, the activelayer 12 may include AlGaN or AlInGaN. When an electric field having apredetermined voltage or more is applied to ends of the bar-type LED,the bar-type LED emits light based on a recombination of electron-holepairs in active layer 12.

The second conductive semiconductor layer 13 is on the active layer 12and may include a semiconductor layer different from the firstconductive semiconductor layer 11. For example, the second conductivesemiconductor layer 13 may include at least one p-type semiconductorlayer. The second conductive semiconductor layer 13 may include, forexample, at least one of InAlGaN, GaN, AlGaN, InGaN, AlN, or InN. Thesecond conductive semiconductor layer 13 may include a semiconductorlayer doped with a second conductive dopant, e.g., Mg. The material ofsecond conductive semiconductor layer 13 may be different in anotherembodiment.

In some embodiments, the bar-type LED may further include a phosphorlayer, an active layer, a semiconductor layer, and/or an electrodelayer, which are over and/or under each of the first conductivesemiconductor layer 11, the active layer 12, and the second conductivesemiconductor layer 13. Also, the bar-type LED may include insulatingfilm 14. In some embodiments, the insulating film 14 may be omitted.

The insulating film 14 surrounds at least one portion of outercircumferential surfaces of the first conductive semiconductor layer 11,the active layer 12, and/or the second conductive semiconductor layer13. For example, the insulating film 14 may surround the outercircumferential surface of the active layer 12. In some embodiments, theinsulating film 14 may include a transparent insulating material. Forexample, the insulating film 14 may include at least one of SiO₂, Si₃N₄,Al₂O₃, or TiO₂.

The insulating film 14 may prevent a short circuit between the activelayer 12 and the first electrode and/or the second electrode. Formationof the insulating film 14 may also reduce or minimize surface defects ofthe bar-type LED, which may improve lifespan and efficiency. In oneembodiment, a plurality of bar-type LEDs may be formed and denselyarranged. In this case, the insulating film 14 may prevent an undesiredshort circuit between the bar-type LEDs.

The bar-type LED of the embodiments described herein may be used as alight emitting source for various lighting devices, self-luminescentdisplay panels, or other electronic devices.

FIG. 2 illustrates an embodiment of a light emitting device whichincludes one or more bar-type LEDs. Referring to FIG. 2, the lightemitting device includes a timing controller 110, a scan driver 120, adata driver 130, and a light emitting unit 140. When the light emittingdevice is a light emitting display device, the light emitting unit 140may correspond to the entire pixel region of a display panel.

The timing controller 110 receives various control signals and imagedata, from an external source (e.g., a system for transmitting imagedata), for driving light emitting unit 140. The timing controller 110realigns the received image data and transmits the realigned image datato the data driver 130. Also, timing controller 110 generates scancontrol signals and data control signals for driving the scan and datadrivers 120 and 130.

The scan driver 120 receives a scan control signal from the timingcontroller 110 and generates a scan signal corresponding to the scancontrol signal. The scan signal from the scan driver 120 is supplied tounit light emitting regions (e.g., pixels) 142 through scan lines S1 toSn.

The data driver 130 receives a data control signal and image data fromthe timing controller 110 and generates data signals corresponding tothe data control signal and the image data. The data signals are outputfrom the data driver 130 to data lines D1 to Dm. The data signals outputto the data lines D1 to Dm are input to unit light emitting regions 142on a horizontal pixel line selected by the scan signal.

The light emitting unit 140 includes a plurality of unit light emittingregions 142 connected to the scan lines S1 to Sn and the data lines D1to Dm. In one embodiment, the unit light emitting regions 142 maycorrespond to individual pixels.

Each of the unit light emitting regions 142 may include at least onebar-type LED as shown in FIG. 1. For example, each of the unit lightemitting regions 142 may include at least one first color bar-type LED,at least one second color bar-type LED, and/or a third color bar-typeLED. The unit light emitting regions 142 selectively emit light based oncorresponding data signals input from the data lines D1 to Dm when ascan signal is supplied from the scan lines S1 to Sn. For example, eachof the unit light emitting regions 142 may emit light with a luminancecorresponding to the data signals during each frame period. A unit lightemitting region 142 that receives a data signal corresponding to theluminance of black does not emit light during a corresponding frameperiod, thereby displaying black. When light emitting unit 140 is apixel unit of an active light emitting display panel, the light emittingunit 140 may be driven by further receiving first and second pixel powersources as well as the scan and data signals.

FIGS. 3A-3E illustrate various embodiments of a unit light emittingregion of a light emitting device. The unit light emitting region maycorrespond, for example, to a pixel of a passive light emitting displaypanel. For convenience, a jth (j is a natural number) pixel on an ith (iis a natural number) horizontal pixel line is shown in FIGS. 3A-3E. Thepixels in FIGS. 3A-3E may be, for example, red, green, blue, or whitepixels. The pixels may emit light of a different color in anotherembodiment.

Referring to FIG. 3A, a pixel 142 includes a bar-type LED nLED connectedbetween a scan line Si and a data line Dj. In some embodiments, a firstelectrode (e.g., anode electrode) of the bar-type LED nLED may beconnected to the scan line Si. A second electrode (e.g., cathodeelectrode) of the bar-type LED nLED may be connected to the data lineDj. When a voltage equal to or greater than a threshold voltage isapplied between the first electrode and the second electrode, thebar-type LED nLED emits light with a luminance corresponding to themagnitude of the applied voltage. The voltage of a scan signal appliedto the scan line Si and/or a data signal applied to the data line Dj isadjusted, to thereby control light emission of the pixel 142.

Referring to FIG. 3B, in some embodiments, pixel 142 may include atleast two bar-type LEDs nLED connected in parallel. Luminance of thepixel 142 may correspond to the sum of brightnesses of the plurality ofLEDs nLED of the pixel 142. When the pixel 142 includes a plurality ofbar-type LEDs nLED, and particularly a large number of bar-type LEDsnLED, the pixel 142 may still operation even when one or more, but lessthan all, of the bar-type LEDs nLED in the pixel 142 are defective.

Referring to FIG. 3C, the connecting direction of the bar-type LEDs nLEDin the pixel 142 may be different from other embodiments. For example, afirst electrode (anode electrode) of the bar-type LED nLED may beconnected to the data line Dj. A second electrode (cathode electrode) ofthe bar-type LED nLED may be connected to the scan line Si. For example,the direction of a voltage applied between the scan line Si and the dataline Dj in FIG. 3A and the direction of a voltage applied between thescan line Si and the data line Dj in FIG. 3C may be opposite to eachother.

Referring to FIG. 3D, the pixel 142 in FIG. 3D may also include at leasttwo bar-type LEDs nLED connected in parallel.

Referring to FIG. 3E, pixel 142 may include a plurality of bar-type LEDsnLED connected in different directions. For example, the pixel 142 mayinclude at least one bar-type LED nLED having a first electrode (anodeelectrode) connected to the scan line Si and a second electrode (cathodeelectrode) connected to the data line Dj, and at least one bar-type LEDnLED having a first electrode (anode electrode) connected to the dataline Dj and a second electrode (cathode electrode) connected to the scanline Si.

In some embodiments, the pixel 142 in FIG. 3E may be DC driven or ACdriven. When the pixel 142 in FIG. 3E is DC driven, forward connectedbar-type LEDs nLED may emit light and reverse connected LEDs nLED maynot emit light. When the pixel 142 of FIG. 3E is AC driven, forwardconnected bar-type LEDs nLED emit light according to the direction of anapplied voltage. Thus, when the pixel 142 of FIG. 3E is AC driven, thebar-type LEDs nLED in the pixel 142 may alternately emit light accordingto the direction of the applied voltage.

FIGS. 4A to 4C illustrate various circuit embodiments of unit lightemitting regions of a light emitting. The unit light emitting regionsare examples of pixels of an active light emitting display panel.

Referring to FIG. 4A, a pixel 142 includes a pixel circuit 144 connectedat least one bar-type LED nLED. The bar-type LED nLED includes a firstelectrode (e.g., anode electrode) connected to a first pixel powersource ELVDD via the pixel circuit 144, and a second electrode (e.g.,cathode electrode) connected to a second pixel power source ELVSS. Thefirst pixel power source ELVDD and the second pixel power source ELVSSmay have different potentials. For example, the second pixel powersource ELVSS may have a potential lower by a threshold voltage or moreof the bar-type LED nLED than the first pixel power source ELVDD. Eachof the bar-type LEDs nLED emits light with a luminance corresponding toa driving current controlled by pixel circuit 144.

Only one bar-type LED nLED is in pixel 142 in FIG. 4A. In anotherembodiment, pixel 142 may have multiple bar-type LEDs nLED connected inparallel.

In some embodiments, the pixel circuit 144 may include first and secondtransistors M1 and M2 and a storage capacitor Cst. The structure of thepixel circuit 144 may be different in another embodiment.

The first transistor (switching transistor) M1 includes a firstelectrode connected to a data line Dj and a second electrode connectedto a first node N1. The first and second electrodes of the firsttransistor M1 are electrodes different from each other. For example, thefirst electrode may be a source electrode and the second electrode maybe a drain electrode. A gate electrode of the first transistor M1 isconnected to a scan line Si. The first transistor M1 is turned on when ascan signal having a voltage (e.g., a low voltage) at which the firsttransistor M1 can be turned on is supplied from the scan line Si. Thedata line Dj and the first node N1 are therefore electrically connectedto each other. A data signal of a corresponding frame supplied to thedata line Dj is transmitted to the first node N1. The data signaltransmitted to the first node N1 is charged in the storage capacitorCst.

The second transistor (driving transistor) M2 has a first electrodeconnected to the first pixel power source ELVDD and a second electrodeconnected to the first electrode of the bar-type LED nLED. A gateelectrode of the second transistor M2 is connected to the first node N1.The second transistor M2 controls the amount of driving current suppliedto the bar-type LED nLED based on a voltage of the first node N1.

The storage capacitor Cst has a first electrode connected to the firstpixel power source ELVDD and a second electrode connected to the firstnode N1. The storage capacitor Cst charges a voltage corresponding tothe data signal supplied to the first node N1 and maintains the chargedvoltage until a data signal of a next frame is supplied.

Thus, the pixel circuit 144 in FIG. 4A has a relatively simplestructure, including the first transistor M1 for transmitting a datasignal to the pixel 142, the storage capacitor Cst for storing the datasignal, and the second transistor M2 for supplying, to the bar-type LEDnLED, a driving current corresponding to the data signal. The structureof the pixel circuit 144 may be different in another embodiment. Forexample, the pixel circuit 144 may include at least one transistorelement (such as a transistor element for compensating a thresholdvoltage of the second transistor M2, a transistor element forinitializing the first node N1, and/or a transistor element forcontrolling a light emission time) or other circuit elements such as aboosting capacitor for boosting the voltage of the first node N1.

The transistors in the pixel circuit 144 are illustrated as p-typetransistors in FIG. 4A. In another embodiment, at least one of thetransistors in the pixel circuit 144 may be an n-type transistor.

Referring to FIG. 4B, the first and second transistors M1 and M2 aren-type transistors. The structure and/or operation of a pixel circuit144 in FIG. 4B may be similar to pixel circuit 144 in FIG. 4A, exceptthat the connecting positions of some components are changed due to thedifferent transistor type.

Referring to FIG. 4C, a pixel 142 may include a plurality of bar-typeLEDs nLED connected in different directions. The pixel 142 may be DCdriven or AC driven, for example, as described in FIG. 3E.

FIG. 5 illustrates another embodiment of a unit light emitting region ofa light emitting device. A pixel of a light emitting display panel mayinclude the light emitting device in FIG. 5. In one embodiment, a onebar-type LED may be provided in the unit light emitting region in FIG.5. In another embodiment, a plurality of bar-type LEDs may be in theunit light emitting region. FIG. 6 is a sectional view taken along lineI-I′ in FIG. 5.

Referring to FIG. 5, the bar-type LED is aligned in the horizontaldirection. In another embodiment, alignment of the bar-type LED may bedifferent, e.g., the bar-type LED may be aligned in an oblique directionbetween first and second electrodes.

Referring to FIGS. 5 and 6, the unit light emitting region (e.g., apixel 142) includes at least one pair of first and second electrode 210and 220 spaced apart from each other on a substrate 200, and at leastone bar-type LED 230 electrically connected between the first and secondelectrodes 210 and 220. The number of first and second electrodes 210and 220 in the unit light emitting region (pixel) 142 and/or the numberof bar-type LEDs 230 in the unit light emitting region 142 may bedifferent in another embodiment. In some embodiments, unit lightemitting region 142 may further include a conductive contact layer 240.

The first electrode 210 and the second electrode 220 are spaced apartfrom each other. In some embodiments, the first and second electrodes210 and 220 may be spaced apart from each other at a distance shorterthan the length of the bar-type LED 230. For example, the first andsecond electrodes 210 and 220 may be spaced apart from each other at asufficient distance that ends of the bar-type LED 230 are connectedbetween the first and second electrodes 210 and 220, while being stablylocated on the first and second electrodes 210 and 220, respectively. Inanother embodiment, when there exists another structure for electricallyconnecting the first and second electrodes 210 and 220 to the bar-typeLED 230, the first and second electrode 210 and 220 may be spaced apartfrom each other at a distance equal to or greater than the length of thebar-type LED 230.

In some embodiments, the first and second electrodes 210 and 220 aredisposed on the same plane, and may have the same height. If the firstand second electrodes 210 and 220 have the same height, the bar-type LED230 can be more stably located on the first and second electrodes 210and 220.

The first electrode 210 is connected to a first electrode line and thesecond electrode 220 is connected to a second electrode line, to receivea predetermined power source or signal. For example, in the case of apassive light emitting device, the first electrode 210 may be connectedto a scan line S to receive a scan signal and the second electrode 220may be connected to a data line D to receive a data signal. In someembodiments, in the case of an active light emitting device, at leastone of the first electrode 210 or the second electrode 220 may beconnected to the pixel circuit 144 as at least one of FIGS. 4A to 4C.

In a process of at least aligning the bar-type LED 230 during afabricating process of the light emitting device, the first and secondelectrodes 210 and 220 may be electrically connected to first and secondshorting bars, respectively. The first shorting bar may be commonlyconnected to first electrodes of a plurality of bar-type LEDs 230 in aplurality of unit light emitting regions 142. The second shorting barmay be commonly connected to second electrodes of the plurality ofbar-type LEDs 230.

When the bar-type LEDs 230 in the unit light emitting regions 142 are tobe independently driven after the light emitting device is fabricated,connection between the first and second electrodes 210 and 220 of theplurality of bar-type LEDs 230 and the first and second shorting barsmay be cut off. For example, the first and second shorting bars may beprovided at the outside of a scribing line of a light emitting displaypanel, in which the light emitting unit 140 in FIG. 2 is formed. As aresult, the first and second electrodes 210 and 220 may be separatedfrom the first and second shorting bars at the same time when a scribingprocess is performed.

In some embodiments, the bar-type LED 230 may have one end on the firstelectrode 210 and another end on the second electrode 220. Theconductive contact layer 240 may stably connect the bar-type LED 230electrically and/or physically to the first and second electrodes 210and 220. In some embodiments, the conductive contact layer 240 may beprovided on ends of the bar-type LED 230.

The conductive contact layer 240 may include a transparent conductivematerial (e.g., ITO, IZO, or ITZO) to allow light emitted from thebar-type LED 230 to be transmitted therethrough. In another embodiment,the conductive contact layer 240 may include a different material or theconductive contact layer 240 may be omitted.

FIG. 7 illustrates another embodiment of a unit light emitting region ofa light emitting device. Referring to FIG. 7, the unit light emittingregion 142 includes a plurality of bar-type LEDs. For example, the unitlight emitting region 142 may include a first bar-type LED 230 a, asecond bar-type LED 230 b, and a third bar-type LED 230 c between atleast one pair of first and second electrodes 210 and 220. In anotherembodiment, the unit light emitting region 142 may include at least twobar-type LEDs in different layers among the at least one first bar-typeLED 230 a, the at least one second bar-type LED 230 b, and the at leastone third bar-type LED 230 c.

In some embodiments, the first bar-type LED 230 a, the second bar-typeLED 230 b, and the third bar-type LED 230 c may be provided or formed indifferent layers on the substrate (e.g., 200 of FIG. 6), respectively.For example, the first bar-type LED 230 a, the second bar-type LED 230b, and the third bar-type LED 230 c may be in first, second, and thirdlayers on the substrate 200, respectively. In addition, an insulatinglayer may be between the first bar-type LED 230 a, the second bar-typeLED 230 b, and the third bar-type LED 230 c.

In some embodiments, the first bar-type LED 230 a, the second bar-typeLED 230 b, and the third bar-type LED 230 c may be LEDs of differentcolors. In order to prevent mutual light interference, the bar-type LED230 a, 230 b, or 230 c emitting light of a relatively longer wavelengthmay be in a lower layer close to the substrate 200. The bar-type LED 230a, 230 b, or 230 c emitting light of a relatively short wavelength maybe in an upper layer. For example, when assuming that the first, second,and third layers are sequentially located from a lower portion close tothe substrate 200, red, green, and blue bar-type LEDs are in the first,second, and third layers, respectively. For example, the first bar-typeLED 230 a may be a red bar-type LED, the second bar-type LED 230 b maybe a green bar-type LED, and the third bar-type LED 230 c may be a bluebar-type LED. However, the stacking order of the first bar-type LED 230a, the second bar-type LED 230 b, and the third bar-type LED 230 c isnot necessarily determined based on wavelengths. In addition, thestacking height of the first bar-type LED 230 a, the second bar-type LED230 b, and the third bar-type LED 230 c may be different in anotherembodiment.

As described above, the unit light emitting region according to thepresent embodiment has a stack structure in which a plurality ofbar-type LEDs 230 a, 230 b, and 230 c are in a plurality of layers. Atleast one of the bar-type LEDs 230 a, 230 b, and 230 c may beelectrically connected between the first and second electrodes 210 and220, and one end of each of the others may be electrically floated. Forexample, the first bar-type LED 230 a may be electrically connectedbetween the first and second electrodes 210 and 220. The first bar-typeLED 230 a may be activated, when a driving voltage equal to or greaterthan a threshold voltage is applied between the first and secondelectrodes 210 and 220, to emit light of a first color.

In some embodiments, at least one end of the second bar-type LED 230 band the third bar-type LED 230 c may be electrically floated. Thus, eventhough the driving voltage is applied to the first and second electrodes210 and 220, the second bar-type LED 230 b and the third bar-type LED230 c maintain a non-activated state.

The second bar-type LED 230 b and the third bar-type LED 230 c may serveas scattering particles for scattering light. For example, when thefirst bar-type LED 230 a emits light, the second bar-type LED 230 b andthe third bar-type LED 230 c may scatter, at various angles, lightemitted from the first bar-type LED 230 a. Accordingly, it is possibleto improve light emission efficiency of the light emitting device.

The conductive contact layer 240 in FIGS. 5 and 6 is not in FIG. 7. Insome embodiments, the conductive contact layer 240 may be additionallyprovided. For example, the conductive contact layer 240 may beadditionally provided at connecting portions between the ends of thefirst bar-type LED 230 a and the first and second electrodes 210 and220.

FIG. 8A is a sectional view illustrating one region of a light emittingdevice according to an embodiment. FIG. 8B illustrating a plan view ofthe one region of the light emitting device.

In FIG. 8A, first to third bar-type LEDs at least partially overlap eachother for each unit light emitting region, in order to show positions ofthe first to third bar-type LEDs for every layer. For example, at leastone portion of the first to third bar-type LEDs may be arbitrarilydisposed on a predetermined layer. FIG. 8B shows that the other bar-typeLEDs, except a selectively aligned bar-type LED, may be arbitrarilylocated in a light emitting unit.

Referring to FIG. 8A, the light emitting device includes a plurality ofunit light emitting regions on a substrate 200. For example, the lightemitting device may include a first unit light emitting region 142 a, asecond unit light emitting region 142 b, and a third unit light emittingregion 142 c, which are continuously disposed in a light emitting unit(e.g., 140 of FIG. 2) on the substrate 200. In some embodiments, a powerline or signal lines (e.g., a data line, etc.) and/or a pixel defininglayer, etc., may be additionally provided between the unit lightemitting regions 142 a, 142 b, and 142 c.

At least one of the unit light emitting regions 142 a, 142 b, and 142 cincludes a pair of first and second electrodes 210 and 220 spaced apartfrom each other, and a plurality of bar-type LEDs 230 a, 230 b, and/or230 c in at least two different layers. For example, each of the unitlight emitting regions 142 a, 142 b, and 142 c may include at least onepair of first and second electrodes 210 and 220, at least one firstbar-type LED 230 a in a first layer over the first and second electrodes210 and 220, at least one second bar-type LED 230 b in a second layerover the first layer, and at least one third bar-type LED 230 c in athird layer over the second layer. In one embodiment, at least one ofthe unit light emitting regions 142 a, 142 b, and 142 c includes atleast one first bar-type LED 230 a in the first layer and at least onesecond bar-type LED 230 b in the second layer, and may not include thethird bar-type LED 230 c.

In some embodiments, an insulating layer 250 may be between and/or overthe bar-type LEDs 230 a, 230 b, and 230 c in different layers. Forexample, a first insulating layer 252 may be between the first bar-typeLED 230 a and the second bar-type LED 230 b. A second insulating layer254 may be between the second bar-type LED 230 b and the third bar-typeLED 230 c. In addition, a third insulating layer 256 may be over thethird bar-type LED 230 c.

In some embodiments, the first bar-type LED 230 a, the second bar-typeLED 230 b, and the third bar-type LED 230 c, which are in differentlayers, may be LEDs of different colors. For example, the first bar-typeLED 230 a may be a bar-type LED emitting light of a first color (e.g.,red) and the second bar-type LED 230 b may be a bar-type LED emittinglight of a second color (e.g., green). In addition, the third bar-typeLED 230 c may be a bar-type LED emitting light of a third color (e.g.,blue).

At least one of the bar-type LEDs 230 a, 230 b, and/or 230 c in each ofthe unit light emitting regions 142 a, 142 b, and 142 c is electricallyconnected between the first electrode 210 and the second electrode 220.For example, the first bar-type LED 230 a may be electrically connectedbetween the first electrode 210 and the second electrode 220 in thefirst unit light emitting region 142 a. In the first unit light emittingregion 142 a, at least one end of the second and third bar-type LEDs 230b and 230 c may be electrically floated. In this case, the second andthird bar-type LEDs 230 b and 230 c of the first unit light emittingregion 142 a maintain the non-activated state regardless of whether adriving voltage is applied. If the driving voltage is applied to thefirst unit light emitting region 142 a, the first bar-type LED 230 a mayemit light of the first color in the first unit light emitting region142 a.

In some embodiments, the second bar-type LED 230 b may be electricallyconnected between the first electrode 210 and the second electrode 220in the second unit light emitting region 142 b. In the second unit lightemitting region 142 b, at least one end of the first and third bar-typeLEDs 230 a and 230 c may be electrically floated. In this case, thefirst and third bar-type LEDs 230 a and 230 c of the second unit lightemitting region 142 b maintain the non-activated state regardless ofwhether a driving voltage is applied. If the driving voltage is appliedto the second unit light emitting region 230 b, the second bar-type LED230 b may emit light of the second color in the second unit lightemitting region 142 b.

In some embodiments, the third bar-type LED 230 c may be electricallyconnected between the first electrode 210 and the second electrode 220in the third unit light emitting region 142 c. In the third unit lightemitting region 142 c, at least one end of the first and second bar-typeLEDs 230 a and 230 b may be electrically floated. In this case, thefirst and second bar-type LEDs 230 a and 230 b of the third unit lightemitting region 142 c maintain the non-activated state regardless ofwhether a driving voltage is applied. If the driving voltage is appliedto the third unit light emitting region 142 c, the third bar-type LED230 c may emit light of the third color in the third unit light emittingregion 142 c. The first to third unit light emitting regions 142 a, 142b, and 142 c, which emit light of different colors, may correspond toone unit pixel of the light emitting device.

In some embodiments, a first contact electrode 262 may be buried in afirst contact hole CH1 penetrating the first, second, and thirdinsulating layers 252, 254, and 256. The first contact hole CH1 exposesat least one portion of the first electrode 210. The first contactelectrode 262 electrically connects, to the first electrode 210, one endof at least one of the first to third bar-type LEDs 230 a, 230 b, and230 c in each of the unit light emitting regions 142 a, 142 b, and 142c. For example, the first contact electrode 262 may electricallyconnect, to the first electrode 210, one ends of the bar-type LEDs 230a, 230 b, and 230 c overlapping the first electrode 210.

In some embodiments, a second contact electrode 264 may be buried in asecond contact hole CH2 penetrating the first, second, and thirdinsulating layers 252, 254, and 256. The second contact hole CH2 exposesat least one portion of the second electrode 220. The second contactelectrode 264 electrically connects, to the second electrode 220, oneend of at least one of the first to third bar-type LEDs 230 a, 230 b,and 230 c in each of the unit light emitting regions 142 a, 142 b, and142 c. For example, the second contact electrode 264 may electricallyconnect, to the second electrode 220, the other ends of the bar-typeLEDs 230 a, 230 b, and 230 c overlapping with the second electrode 220.

In the sectional view of FIG. 8A, lengths of the first to third bar-typeLEDs 230 a, 230 b, and 230 c in each of the unit light emitting regions142 a, 142 b, and 142 c are different from one another. In someembodiments, the first to third bar-type LEDs 230 a, 230 b, and 230 cmay have lengths similar or substantially equal to one another. When thebar-type LEDs 230 a, 230 b, and/or 230 c, having at least one floatedend in each of the unit light emitting regions 142 a, 142 b, and 142 c,are in oblique directions, the bar-type LEDs 230 a, 230 b, and/or 230 cmay be shown as if their lengths are short.

Referring to FIG. 8B, the bar-type LEDs 230 a, 230 b, and/or 230 c,having at least one floated end in each of the unit light emittingregions 142 a, 142 b, and 142 c, are arbitrarily disposed between thefirst and second electrodes 210 and 220. For example, the bar-type LEDs230 a, 230 b, and/or 230 c may be in oblique directions.

As described above, when a light emitting device has a stack structurewith first to third bar-type LEDs 230 a, 230 b, and 230 c in differentlayers, light emission efficiency of the light emitting device may beimproved as in FIG. 7. In addition, the stacked structure of the lightemitting device allows a corresponding fabrication method to be easilyperformed.

FIG. 9 is a sectional view illustrating one region of a light emittingdevice according to another embodiment. Referring to FIG. 9, circuitelements such as transistors TFT and an insulating layer 270 coveringthe circuit elements may be further provided under first and secondelectrodes 210 and 220 and bar-type LEDs 230 a, 230 b, and 230 c. Forexample, the transistors TFT may be electrically connected to the firstelectrode 210 through via holes VH formed in the insulating layer 270.

In addition, other transistors and/or a capacitor, etc., may be formedunder the first and second electrodes 210 and 220 and the bar-type LEDs230 a, 230 b, and 230 c. For example, circuit elements of a pixelcircuit as shown in any of FIGS. 4A-4C may be in each of unit lightemitting regions 142 a, 142 b, and 142 c. In some embodiments, areflective layer, etc., may be under each of the bar-type LEDs 230 a,230 b, and 230 c.

FIGS. 10A-10E are sectional views illustrating various stages of anembodiment of a method for fabricating the light emitting device shownin FIG. 8A. FIGS. 11A-11C are plan views of one region of the lightemitting device in FIGS. 10A-10C.

In FIGS. 10A-10E, the first to third bar-type LEDs at least partiallyoverlap each other for each unit light emitting region, thus showingpositions of the first to third bar-type LEDs for every layer. In oneembodiment, at least one portion of the first to third bar-type LEDs maybe on a predetermined layer. In addition, FIGS. 11A-11C show that theother bar-type LEDs, except a selectively aligned bar-type LED, may bein a light emitting unit.

Referring to FIGS. 10A and 11A, at least one pair of first and secondelectrodes 210 and 220 are first formed in each of unit light emittingregions 142 a, 142 b, and 142 c on a substrate 200. At least one firstbar-type LED 230 a is then injected and/or scattered into the unit lightemitting regions 142 a, 142 b, and 142 c. An inkjet printing techniqueis a non-restrictive example of injecting the first bar-type LED 230 a.For example, a solution including a plurality of first bar-type LEDs 230a may be dropped or coated on the front of a light emitting unitincluding the unit light emitting regions 142 a, 142 b, and 142 c. Thesolution may have an ink or paste phase. For example, a photoresist ororganic layer containing a solvent may be used as the solution.

After the first bar-type LEDs 230 a are injected, or at the same timewhen the first bar-type LEDs 230 a are injected, at least one firstbar-type LED 230 a may be aligned between the first and secondelectrodes 210 and 220 in at least one unit light emitting region (142a, 142 b, and/or 142 c). For example, as a DC or AC voltage is appliedto the first and second electrodes 210 and 220 of a desired unit lightemitting region, e.g., a first unit light emitting region 142 a,self-alignment of the first bar-type LED 230 a may be induced such thatboth ends of the first bar-type LED 230 a are respectively located onthe first and second electrodes 210 and 220 on the first unit lightemitting region 142 a.

When a voltage is applied to the first and second electrodes 210 and220, dipolarity is induced to the first bar-type LED 230 a by anelectric field formed between the first and second electrodes 210 and220. Accordingly, the first bar-type LED 230 a is self-aligned betweenthe first and second electrodes 210 and 220.

A first insulating layer 252 is formed over the first bar-type LEDs 230a. The injection or coating of an insulating material for forming thefirst insulating layer 252 may be simultaneously performed with theinjection of the first bar-type LEDs 230 a, or may be performed afterthe injection of the first bar-type LEDs 230 a. For example, as asolution including the first bar-type LEDs 230 a and an insulatingmaterial for forming the first insulating layer 252 is dropped, theinjection of the first bar-type LEDs 230 a and the injection or coatingof the insulating material for forming the first insulating layer 252may be simultaneously performed. After the first bar-type LEDs 230 a areself-aligned, the insulating material may be cured to form the firstinsulating layer 252.

In some embodiments, after the injection and self-alignment of the firstbar-type LEDs 230 a are completed, the insulating material may bedropped or coated on the first bar-type LEDs 230 a, thereby forming thefirst insulating layer 252.

Referring to FIGS. 10B and 11B, at least one second bar-type LED 230 bis injected into the unit light emitting regions 142 a, 142 b, and 142 con which the first insulating layer 252 is formed. For example, asolution including a plurality of second bar-type LEDs 230 b may bedropped or coated on the front of the light emitting unit including theunit light emitting regions 142 a, 142 b, and 142 c.

After the second bar-type LEDs 230 b are injected or at the same timewhen the second bar-type LEDs 230 b are injected, at least one secondbar-type LED 230 b may be aligned between the first and secondelectrodes 210 and 220 in at least one unit light emitting region 142 a,142 b, and/or 142 c. For example, as a DC or AC voltage is applied tothe first and second electrodes 210 and 220 of the second unit lightemitting region 142 b, self-alignment of the second bar-type LED 230 bmay be induced such that both ends of the second bar-type LED 230 b arerespectively located on the first and second electrodes 210 and 220 ofthe second unit light emitting region 142 b. A second insulating layer254 is formed over the second bar-type LEDs 230 b.

Referring to FIGS. 10C and 11C, at least one third bar-type LED 230 c isinjected into the unit light emitting regions 142 a, 142 b, and 142 c onwhich the second insulating layer 254 is formed. For example, a solutionincluding a plurality of third bar-type LEDs 230 c may be dropped orcoated on the front of the light emitting unit including the unit lightemitting regions 142 a, 142 b, and 142 c.

After the third bar-type LEDs 230 c are injected or at the same timewhen the third bar-type LEDs 230 c are injected, at least one thirdbar-type LED 230 c may be aligned between the first and secondelectrodes 210 and 220 formed in at least one unit light emitting region142 a, 142 b, and/or 142 c. For example, as a DC or AC voltage isapplied to the first and second electrodes 210 and 220 of the third unitlight emitting region 142 c, self-alignment of the third bar-type LED230 c may be induced such that ends of the third bar-type LED 230 c arerespectively located on the first and second electrodes 210 and 220 ofthe third unit light emitting region 142 c. A third insulating layer 256is formed over the third bar-type LEDs 230 c.

Referring to FIG. 10D, after the first, second, and third bar-type LEDs230 a, 230 b, and 230 c are formed, a first contact hole CH1 and asecond contact hole CH2 are formed in each of the unit light emittingregions 142 a, 142 b, and 142 c. In some embodiments, the first contacthole CH1 and the second contact hole CH2 may penetrate the first,second, and third insulating layers 252, 254, and 256. For example, thefirst contact hole CH1 may penetrate the first, second, and thirdinsulating layers 252, 254, and 256 to expose one end of at least one ofthe first, second, and third bar-type LEDs 230 a, 230 b, and 230 c andat least one region of the first electrode 210. The second contact holeCH2 may penetrate the first, second, and third insulating layers 252,254, and 256 to expose the other end of at least one of the first,second, and third bar-type LEDs 230 a, 230 b, and 230 c and at least oneregion of the second electrode 220.

Referring to FIG. 10E, at the same time when a first contact electrode262 is formed to be buried in the first contact hole CH1, a secondcontact electrode 264 is formed to be buried in the second contact holeCH2. In some embodiments, the first contact electrode 262 and the secondcontact electrode 264 may be sequentially formed. Accordingly, the firstcontact electrode 262 electrically connects the first electrode 210 toone end of at least one of the first, second, and third bar-type LEDs230 a, 230 b, or 230 c. For example, the first contact electrode 262 ofthe first unit light emitting region 142 a electrically connects thefirst electrode 210 to one end of at least one first bar-type LED 230 a.The second contact electrode 264 electrically connects the secondelectrode 220 to the other end of at least one of the first, second, andthird bar-type LEDs 230 a, 230 b, or 230 c. For example, the secondcontact electrode 264 of the first unit light emitting region 142 aelectrically connects the second electrode 220 to the other end of atleast one first bar-type LED 230 a.

As described above, a light emitting device having a stack structure isconfigured by disposing the first, second, and third bar-type LEDs 230a, 230 b, and 230 c in different layers. A process for fabricating thelight emitting device may therefore be easily performed.

In a comparative example, if the size of each of the unit light emittingregions 142 a, 142 b, and 142 c is relatively small when only a bar-typeLED 230 a, 230 b, or 230 c of a desired color is to be injected intoeach of the unit light emitting regions 142 a, 142 b, and 142 c, it maybe difficult to inject a desired bar-type LED 230 a, 230 b, or 230 c ata desired position. For example, when a solution including the bar-typeLED 230 a, 230 b, or 230 c is to be injected into a desired unit lightemitting region 142 a, 142 b, or 142 c using an inkjet printingtechnique, a high-resolution printing technique performed in units ofsub-pixels may be required. Therefore, the level of difficulty of theprocess may be increased. In addition, since cohesion and precipitationof the bar-type LED 230 a, 230 b, and/or 230 c easily occur, it may bedifficult to inject the bar-type LED 230 a, 230 b, and/or 230 c intoeach of the unit light emitting regions 142 a, 142 b, and 142 c.

However, in one or more embodiments, when the first to third bar-typeLEDs 230 a, 230 b, and 230 c are disposed in different layers, the firstbar-type LEDs 230 a, the second bar-type LEDs 230 b, or the thirdbar-type LEDs 230 c may be dropped or scattered on the front of thelight emitting unit including the unit light emitting regions 142 a, 142b, and 142 c for each layer, without distinguishing the unit lightemitting regions 142 a, 142 b, and 142 c from one another. Accordingly,the process for fabricating the light emitting device may be easilyperformed, and uniformity of the bar-type LEDs 230 a, 230 b, and 230 bmay be improved.

In addition, after the bar-type LEDs 230 a, 230 b, and/or 230 c areinjected into the light emitting unit, the voltage applied to the firstand second electrodes 210 and 220 for each of the unit light emittingregions 142 a, 142 b, and 142 c is controlled, so that only a desiredkind of bar-type LED 230 a, 230 b, and/or 230 c may be selectivelyaligned between the first and second electrodes 210 and 220 of acorresponding unit light emitting region 142 a, 142 b, or 142 c.

In some embodiments, when the first to third bar-type LEDs 230 a, 230 b,and 230 c are self-aligned, magnitudes of voltages (e.g., the absolutevalues of voltages) applied to the first and second electrodes 210 and220 of corresponding unit light emitting regions 142 a, 142 b, and 142 cmay be the same or different from one another. For example, themagnitude of a voltage applied to the first and second electrodes 210and 220 of a corresponding unit light emitting region 142 a, 142 b, or142 c may be adjusted based on a distance variation between the firstand second electrodes 210 and 220 and the bar-type LED 230 a, 230 b, or230 c to be self-aligned in each of the unit light emitting regions 142a, 142 b, and 142 c. For example, the magnitude of a voltage applied foreach of the unit light emitting regions 142 a, 142 b, and 142 c may beset such that, when the first to third bar-type LEDs 230 a, 230 b, and230 c are self-aligned, the intensities of electric fields applied tothe first to third bar-type LEDs 230 a, 230 b, and 230 c are thesubstantially same.

In this case, the magnitude of a voltage applied to the first and secondelectrodes 210 and 220 of the second unit light emitting region 142 bwhen the second bar-type LEDs 230 b are self-aligned may be greater thanthat of a voltage applied to the first and second electrodes 210 and 220of the first unit light emitting region 142 a when the first bar-typeLEDs 230 a are self-aligned. For example, a first voltage may be appliedbetween the first and second electrodes 210 and 220 of the first unitlight emitting region 142 a in the operation of self-aligning the firstbar-type LEDs 230 a, and a second voltage may be applied between thefirst and second electrodes 210 and 220 of the second unit lightemitting region 142 b in self-aligning the second bar-type LEDs 230 b.

In addition, the magnitude of a voltage applied to the first and secondelectrodes 210 and 220 of the third unit light emitting region 142 cwhen the third bar-type LEDs 230 c are self-aligned may be greater thanthat of a voltage applied to the first and second electrodes 210 and 220of the second unit light emitting region 142 b when the second bar-typeLEDs 230 b are self-aligned. For example, a third voltage greater thanthe first and second voltages may be applied between the first andsecond electrodes 210 and 220 of the third unit light emitting region142 c in the operation of self-aligning the third bar-type LEDs 230 c.Accordingly, when the first to third bar-type LEDs 230 a, 230 b, and 230c are self-aligned, a uniform electric field may be applied to the firstto third bar-type LEDs 230 a, 230 b, and 230 c.

FIG. 12 is a sectional view illustrating one region of a light emittingdevice according to another embodiment. Referring to FIG. 12, first endsof first, second, and third bar-type LEDs 230 a, 230 b, and 230 c arecommonly connected to a first electrode 210 through a first contactelectrode 262, and the other ends of the first, second, and thirdbar-type LEDs 230 a, 230 b, and 230 c are commonly connected to a secondelectrode 220 through a second contact electrode 264. Thus, in someembodiments, the first, second, and third bar-type LEDs 230 a, 230 b,and 230 c may be commonly connected in a structure in which at least twobar-type LEDs 230 a, 230 b, and 230 c formed in different layers in eachof unit light emitting regions 142 a, 142 b, and 142 c may be connectedin parallel between the first and second electrodes 210 and 220.

In this case, each of the unit light emitting regions 142 a, 142 b, and142 c may emit white light. A lighting device may be used as an exampleof the light emitting device to which such a structure may be applied.In another embodiment, the structure of FIG. 12 may be applied to alight emitting display device. For example, the unit light emittingregions 142 a, 142 b, and 142 c may constitute pixels emitting whitelight, respectively. In this case, as a color filter is disposed on asurface from light is emitted, pixels of desired colors may beimplemented.

In the light emitting device according to the present embodiment, if adriving voltage is applied to the first and second electrodes 210 and220 of at least one unit light emitting region 142 a, 142 b, and/or 142c, the first to third bar-type LEDs 230 a, 230 b, and 230 c of thecorresponding unit light emitting region 142 a, 142 b, and/or 142 c emitlight of corresponding colors, e.g., red, green, and blue, respectively.Accordingly, the corresponding unit light emitting region 142 a, 142 b,and/or 142 c emits white light. In the light emitting device, all of thebar-type LEDs 230 a, 230 b, and 230 c emit light in the same area.Accordingly, it is possible to sufficiently secure a light emissionarea.

FIGS. 13A-13E are sectional views of various stages of anotherembodiment of a method for fabricating the light emitting device in FIG.12. Referring to FIG. 13A, after first bar-type LEDs 230 a are injected,a voltage is applied to first and second electrodes 210 and 220 of eachof first to third unit light emitting regions 142 a, 142 b, and 142 c.Accordingly, ends of at least one first bar-type LED 230 a are alignedon the first and second electrodes 210 and 220 in all of the first,second, and third unit light emitting regions 142 a, 142 b, and 142 c.For example, the first bar-type LED 230 a is aligned to be electricallyconnected between the first and second electrodes 210 and 220. In thiscase, a conductive contact layer for stably connecting ends of the firstbar-type LED 230 a physically and/or electrically to the first andsecond electrodes 210 and 220 may be further formed.

Referring to FIG. 13B, after second bar-type LEDs 230 b are injected, avoltage is applied to the first and second electrodes 210 and 220 ofeach of the first to third unit light emitting regions 142 a, 142 b, and142 c. Accordingly, ends of at least one second bar-type LED 230 b arealigned on the first and second electrodes 210 and 220 in all of thefirst, second, and third unit light emitting regions 142 a, 142 b, and142 c.

Referring to FIG. 13C, after third bar-type LEDs 230 c are injected, avoltage is applied to the first and second electrodes 210 and 220 ofeach of the first to third unit light emitting regions 142 a, 142 b, and142 c. Accordingly, ends of at least one third bar-type LED 230 c arealigned on the first and second electrodes 210 and 220 in all of thefirst, second, and third unit light emitting regions 142 a, 142 b, and142 c.

Referring to FIG. 13D, a first contact hole CH1 penetrating first,second, and third insulating layers 252, 254, and 256 is formed toexpose the first electrode 210 and first ends of the first, second, andthird bar-type LEDs 230 a, 230 b, and 230 c. Simultaneously, a secondcontact hole CH2 penetrating the first, second, and third insulatinglayers 252, 254, and 256 may be formed to expose the second electrode220 and second ends of the first, second, and third bar-type LEDs 230 a,230 b, and 230 c.

Referring to FIG. 13E, a first contact electrode 262 is formed in thefirst contact hole CH1, and simultaneously, a second contact electrode264 is formed in the second contact hole CH2. In some embodiments, thefirst contact electrode 262 and the second contact electrode 264 may besequentially formed.

In some embodiments, the first contact electrode 262 may commonlyconnect the first electrode 210 to first ends of the first, second, andthird bar-type LEDs 230 a, 230 b, and 230 c. In addition, the secondcontact electrode 264 may commonly connect the second electrode 220 tosecond ends of the first, second, and third bar-type LEDs 230 a, 230 b,and 230 c.

FIG. 14 is a sectional view illustrating one region of a light emittingdevice according to another embodiment. Referring to FIG. 14, anindividual driving electrode may be provided for each of first bar-typeLEDs 230 a, second bar-type LEDs 230 b, and third bar-type LEDs 230 c.For example, the light emitting device may include first and secondelectrodes 210 and 220 respectively connected first ends and the secondends of the first bar-type LEDs 230 a, third and fourth electrodes 280and 290 respectively connected first ends and the second ends of thesecond bar-type LEDs 230 b, and fifth and sixth electrodes 300 and 310respectively connected to first ends and the second ends of the thirdbar-type LEDs 230 c.

In some embodiments, electrodes connected to corresponding ends of thebar-type LEDs 230 a, 230 b, and/or 230 c connected, in series orparallel to each other, may be patterned such that the electrodes may beconnected integrally with each other. In FIG. 14, the first and secondelectrodes 210 and 220 connected to ends of the first bar-type LEDs 230are illustrated as separated patterns, so as to represent variousembodiments related to electrode connection structures between thebar-type LEDs 230 a, 230 b, and 230 c disposed in different layers. Inaddition, a structure in which the third, fourth, fifth and/or sixthelectrode 280, 290, 300, and/or 310 connected at least one end of thesecond and third bar-type LEDs 230 b and 230 c is integrally connectedto the third, fourth, fifth and/or sixth electrode 280, 290, 300, and/or310 connected at least one end of adjacent second and third bar-typeLEDs 230 b and 230 c is in FIG. 14. The connection structures of thebar-type LEDs 230 a, 230 b, and 230 c in different layers may bedifferent in other embodiments.

According to this embodiment described above, the first bar-type LEDs230 a, the second bar-type LEDs 230 b, and the third bar-type LEDs 230 cmay be independently driven in each of the unit light emitting regions142 a, 142 b, and 142 c.

FIGS. 15A-15I are sectional views of various stages of method forfabricating the light emitting device in FIG. 14. Referring to FIG. 15A,after first bar-type LEDs 230 a are injected, a voltage is applied tofirst and second electrodes 210 and 220 of first, second, and third unitlight emitting regions 142 a, 142 b, and 142 c, thereby aligning thefirst bar-type LEDs 230 a to be electrically connected between the firstand second electrodes 210 and 220.

Referring to FIG. 15B, after second bar-type LEDs 230 b are injected, avoltage is applied to the first and second electrodes 210 and 220 of thefirst, second, and third unit light emitting regions 142 a, 142 b, and142 c, thereby aligning the second bar-type LEDs 230 b.

Referring to FIGS. 15C to 15E, a first conductive layer 320 is formedover the second bar-type LEDs 230 b and a first mask 330 is formed onthe first conductive layer 320. Then, the first conductive layer 320 ispatterned using the first mask 330, thereby forming third and fourthelectrodes 280 and 290. After that, a second insulating layer 254 is atleast formed on the third and fourth electrodes 280 and 290. In someembodiments, the first mask 330 may include a photoresist material. Insome embodiments, the first mask 330 may be etched by a predeterminedthickness, thereby forming the second insulating layer 254.

Referring to FIG. 15F, after third bar-type LEDs 230 c are injected, avoltage is applied to the first and second electrodes 210 and 220 of thefirst, second, and third unit light emitting regions 142 a, 142 b, and142 c, to align the third bar-type LEDs 230 c.

Referring to FIGS. 15G-15I, a second conductive layer 340 is formed overthe third bar-type LEDs 230 c and a second mask 350 is formed on thesecond conductive layer 340. Then, the second conductive layer 340 ispatterned using the second mask 350, thereby forming fifth and sixthelectrodes 300 and 310. Subsequently, a third insulating layer 256 is atleast formed on the fifth and sixth electrodes 300 and 310. In someembodiments, the second mask 350 may include a photoresist material. Insome embodiments, the second mask 350 may be etched by a predeterminedthickness, thereby forming the third insulating layer 256.

FIGS. 16 and 17 are sectional views illustrating one region of lightemitting devices according to other embodiments. Referring to FIG. 16,for at least each of first bar-type LEDs 230 a, second bar-type LEDs 230b, and third bar-type LEDs 230 c, the first bar-type LEDs 230 a, thesecond bar-type LEDs 230 b, and the third bar-type LEDs 230 c may beelectrically connected to driving elements TFTr, TFTg, and TFTb,respectively. According to this embodiment, for at least each of thefirst bar-type LEDs 230 a, the second bar-type LEDs 230 b, and the thirdbar-type LEDs 230 c, the first bar-type LEDs 230 a, the second bar-typeLEDs 230 b, and the third bar-type LEDs 230 c may be independentlydriven.

Referring to FIG. 17, each of first bar-type LEDs 230 a, second bar-typeLEDs 230 b, and third bar-type LEDs 230 c may be electrically connectedto individual driving elements TFTr1 to TFTr3, TFTg1 to TFTg3, and TFTb1to TFTb3. According to this embodiment, each of the first bar-type LEDs230 a, the second bar-type LEDs 230 b, and the third bar-type LEDs 230 cmay be independently driven.

According to one or more embodiments, a plurality of bar-type LEDs aredisposed in different layers of each of a plurality of unit lightemitting regions. Accordingly, a process for fabricating a lightemitting device may be easily performed. In addition, at least oneportion of one or more bar-type LEDs may serve as scattering particles.Accordingly, the light emission efficiency of the light emitting devicecan be improved.

Example embodiments have been disclosed herein, and although specificterms are employed, they are used and are to be interpreted in a genericand descriptive sense only and not for purpose of limitation. In someinstances, as would be apparent to one of ordinary skill in the art asof the filing of the present application, features, characteristics,and/or elements described in connection with a particular embodiment maybe used singly or in combination with features, characteristics, and/orelements described in connection with other embodiments unless otherwisespecifically indicated. Accordingly, it will be understood by those ofskill in the art that various changes in form and details may be madewithout departing from the spirit and scope of the present invention asset forth in the following claims.

What is claimed is:
 1. A light emitting display device, comprising: afirst electrode and a second electrode on a substrate; a first LED onthe first electrode and the second electrode; a third electrodecontacting a first end of the first LED and covering a side of the firstelectrode; and a fourth electrode contacting a second end of the firstLED and covering a side of the second electrode.
 2. The light emittingdisplay device of claim 1, wherein: the third electrode contacts a firstportion of an upper surface of the first LED located on the first end,in a cross-sectional view; and the fourth electrode contacts a secondportion of the upper surface of the first LED located on the second end,in a cross-sectional view.
 3. The light emitting display device of claim2, wherein the first end and the second end are opposite to each otherin a longitudinal direction of the first LED.
 4. The light emittingdisplay device of claim 1, wherein the first electrode and the secondelectrode are located at a same plane.
 5. The light emitting displaydevice of claim 1, wherein the first electrode is connected to a firstelectrode line and the second electrode is connected to a secondelectrode line, to receive power or a signal.
 6. The light emittingdisplay device of claim 1, further comprising a pixel circuit connectedto at least one of the first electrode and the second electrode.
 7. Thelight emitting display device of claim 6, wherein the pixel circuitcomprises a transistor located at a layer between the substrate and thefirst electrode and the second electrode.
 8. The light emitting displaydevice of claim 1, wherein each of the third electrode and the fourthelectrode comprises a transparent conductive material.
 9. The lightemitting display device of claim 1, wherein the first LED comprises abar-type LED aligned in a direction crossing the first electrode and thesecond electrode.
 10. The light emitting display device of claim 9,wherein the first LED is aligned in a horizontal direction or an obliquedirection between the first electrode and the second electrode, in aplan view.
 11. The light emitting display device of claim 1, wherein thefirst electrode and the second electrode are spaced apart from eachother at a distance shorter than a length of the first LED.
 12. Thelight emitting display device of claim 1, further comprising a secondLED located at a different layer from the first LED.
 13. The lightemitting display device of claim 12, further comprising an insulatinglayer interposed between the first LED and the second LED.
 14. The lightemitting display device of claim 12, wherein the first LED and thesecond LED are located at different heights from a surface of thesubstrate.
 15. The light emitting display device of claim 1, wherein athickness in the longitudinal direction of each of the third electrodeand the fourth electrode is less than a thickness in the longitudinaldirection of the first LED.
 16. A light emitting display device,comprising: a first pixel; and a second pixel adjacent to the firstpixel, wherein each of the first pixel and the second pixel comprises: afirst electrode and a second electrode on a substrate; an LED on thefirst electrode and the second electrode; a third electrode contacting afirst end of the LED and covering a side of the first electrode; and afourth electrode contacting a second end of the LED and covering a sideof the second electrode, and wherein the LED in the first pixel and theLED in the second pixel are to emit light of different colors,respectively.
 17. The light emitting display device of claim 16,wherein: the third electrode contacts a first portion of an uppersurface of the LED located on the first end, in a cross-sectional view;and the fourth electrode contacts a second portion of the upper surfaceof the LED located on the second end, in a cross-sectional view.
 18. Thelight emitting display device of claim 16, wherein the first electrodeand the second electrode are located at a same plane.
 19. The lightemitting display device of claim 16, wherein each of the first pixel andthe second pixel further comprises a pixel circuit connected to at leastone of the first electrode and the second electrode.
 20. The lightemitting display device of claim 16, wherein each of the third electrodeand the fourth electrode comprises a transparent conductive material.21. The light emitting display device of claim 16, wherein the firstelectrode and the second electrode are spaced apart from each other at adistance shorter than a length of the LED.